# Implemented in python based on https://github.com/lvmteam/lvm2/blob/master/lib/misc/crc.c

INITIAL_CRC = int.from_bytes(bytearray.fromhex("f5 97 a6 cf"), byteorder="big")


def calc_crc(initial, buf):
    crctab = [
        0x00000000,
        0x77073096,
        0xEE0E612C,
        0x990951BA,
        0x076DC419,
        0x706AF48F,
        0xE963A535,
        0x9E6495A3,
        0x0EDB8832,
        0x79DCB8A4,
        0xE0D5E91E,
        0x97D2D988,
        0x09B64C2B,
        0x7EB17CBD,
        0xE7B82D07,
        0x90BF1D91,
        0x1DB71064,
        0x6AB020F2,
        0xF3B97148,
        0x84BE41DE,
        0x1ADAD47D,
        0x6DDDE4EB,
        0xF4D4B551,
        0x83D385C7,
        0x136C9856,
        0x646BA8C0,
        0xFD62F97A,
        0x8A65C9EC,
        0x14015C4F,
        0x63066CD9,
        0xFA0F3D63,
        0x8D080DF5,
        0x3B6E20C8,
        0x4C69105E,
        0xD56041E4,
        0xA2677172,
        0x3C03E4D1,
        0x4B04D447,
        0xD20D85FD,
        0xA50AB56B,
        0x35B5A8FA,
        0x42B2986C,
        0xDBBBC9D6,
        0xACBCF940,
        0x32D86CE3,
        0x45DF5C75,
        0xDCD60DCF,
        0xABD13D59,
        0x26D930AC,
        0x51DE003A,
        0xC8D75180,
        0xBFD06116,
        0x21B4F4B5,
        0x56B3C423,
        0xCFBA9599,
        0xB8BDA50F,
        0x2802B89E,
        0x5F058808,
        0xC60CD9B2,
        0xB10BE924,
        0x2F6F7C87,
        0x58684C11,
        0xC1611DAB,
        0xB6662D3D,
        0x76DC4190,
        0x01DB7106,
        0x98D220BC,
        0xEFD5102A,
        0x71B18589,
        0x06B6B51F,
        0x9FBFE4A5,
        0xE8B8D433,
        0x7807C9A2,
        0x0F00F934,
        0x9609A88E,
        0xE10E9818,
        0x7F6A0DBB,
        0x086D3D2D,
        0x91646C97,
        0xE6635C01,
        0x6B6B51F4,
        0x1C6C6162,
        0x856530D8,
        0xF262004E,
        0x6C0695ED,
        0x1B01A57B,
        0x8208F4C1,
        0xF50FC457,
        0x65B0D9C6,
        0x12B7E950,
        0x8BBEB8EA,
        0xFCB9887C,
        0x62DD1DDF,
        0x15DA2D49,
        0x8CD37CF3,
        0xFBD44C65,
        0x4DB26158,
        0x3AB551CE,
        0xA3BC0074,
        0xD4BB30E2,
        0x4ADFA541,
        0x3DD895D7,
        0xA4D1C46D,
        0xD3D6F4FB,
        0x4369E96A,
        0x346ED9FC,
        0xAD678846,
        0xDA60B8D0,
        0x44042D73,
        0x33031DE5,
        0xAA0A4C5F,
        0xDD0D7CC9,
        0x5005713C,
        0x270241AA,
        0xBE0B1010,
        0xC90C2086,
        0x5768B525,
        0x206F85B3,
        0xB966D409,
        0xCE61E49F,
        0x5EDEF90E,
        0x29D9C998,
        0xB0D09822,
        0xC7D7A8B4,
        0x59B33D17,
        0x2EB40D81,
        0xB7BD5C3B,
        0xC0BA6CAD,
        0xEDB88320,
        0x9ABFB3B6,
        0x03B6E20C,
        0x74B1D29A,
        0xEAD54739,
        0x9DD277AF,
        0x04DB2615,
        0x73DC1683,
        0xE3630B12,
        0x94643B84,
        0x0D6D6A3E,
        0x7A6A5AA8,
        0xE40ECF0B,
        0x9309FF9D,
        0x0A00AE27,
        0x7D079EB1,
        0xF00F9344,
        0x8708A3D2,
        0x1E01F268,
        0x6906C2FE,
        0xF762575D,
        0x806567CB,
        0x196C3671,
        0x6E6B06E7,
        0xFED41B76,
        0x89D32BE0,
        0x10DA7A5A,
        0x67DD4ACC,
        0xF9B9DF6F,
        0x8EBEEFF9,
        0x17B7BE43,
        0x60B08ED5,
        0xD6D6A3E8,
        0xA1D1937E,
        0x38D8C2C4,
        0x4FDFF252,
        0xD1BB67F1,
        0xA6BC5767,
        0x3FB506DD,
        0x48B2364B,
        0xD80D2BDA,
        0xAF0A1B4C,
        0x36034AF6,
        0x41047A60,
        0xDF60EFC3,
        0xA867DF55,
        0x316E8EEF,
        0x4669BE79,
        0xCB61B38C,
        0xBC66831A,
        0x256FD2A0,
        0x5268E236,
        0xCC0C7795,
        0xBB0B4703,
        0x220216B9,
        0x5505262F,
        0xC5BA3BBE,
        0xB2BD0B28,
        0x2BB45A92,
        0x5CB36A04,
        0xC2D7FFA7,
        0xB5D0CF31,
        0x2CD99E8B,
        0x5BDEAE1D,
        0x9B64C2B0,
        0xEC63F226,
        0x756AA39C,
        0x026D930A,
        0x9C0906A9,
        0xEB0E363F,
        0x72076785,
        0x05005713,
        0x95BF4A82,
        0xE2B87A14,
        0x7BB12BAE,
        0x0CB61B38,
        0x92D28E9B,
        0xE5D5BE0D,
        0x7CDCEFB7,
        0x0BDBDF21,
        0x86D3D2D4,
        0xF1D4E242,
        0x68DDB3F8,
        0x1FDA836E,
        0x81BE16CD,
        0xF6B9265B,
        0x6FB077E1,
        0x18B74777,
        0x88085AE6,
        0xFF0F6A70,
        0x66063BCA,
        0x11010B5C,
        0x8F659EFF,
        0xF862AE69,
        0x616BFFD3,
        0x166CCF45,
        0xA00AE278,
        0xD70DD2EE,
        0x4E048354,
        0x3903B3C2,
        0xA7672661,
        0xD06016F7,
        0x4969474D,
        0x3E6E77DB,
        0xAED16A4A,
        0xD9D65ADC,
        0x40DF0B66,
        0x37D83BF0,
        0xA9BCAE53,
        0xDEBB9EC5,
        0x47B2CF7F,
        0x30B5FFE9,
        0xBDBDF21C,
        0xCABAC28A,
        0x53B39330,
        0x24B4A3A6,
        0xBAD03605,
        0xCDD70693,
        0x54DE5729,
        0x23D967BF,
        0xB3667A2E,
        0xC4614AB8,
        0x5D681B02,
        0x2A6F2B94,
        0xB40BBE37,
        0xC30C8EA1,
        0x5A05DF1B,
        0x2D02EF8D,
    ]

    crc = initial

    for i in range(0, len(buf), 4):
        window = buf[i : i + 4]

        if len(window) == 4:
            value = int.from_bytes(window, byteorder="little")
            crc ^= value

            crc = crctab[crc & 0xFF] ^ crc >> 8
            crc = crctab[crc & 0xFF] ^ crc >> 8
            crc = crctab[crc & 0xFF] ^ crc >> 8
            crc = crctab[crc & 0xFF] ^ crc >> 8
        else:
            for value in window:
                crc ^= value

                crc = crctab[crc & 0xFF] ^ crc >> 8

    return crc
